The 3 Conditions for Combustion
by dietplainlite
Summary: 1. There has to be something flammable. 2. It has to be at the right temperature to ignite. 3. It has to be mixed with some fresh air.


Irene puts her keys in her pocket. She stands just inside the door, breathing quietly, listening, watching.

In the air: Molly's perfume. A fruity body spray mostly consisting of alcohol. The bottle of Daisy by Marc Jacobs Irene had given Molly likely sat on her dresser, only used for special occasions. Irene had bought it on a whim while purchasing her usual scent. The whimsical bottle had immediately called Molly to mind, and the fragrance-citrus with rich, earthy undertones-seemed formulated just for the pathologist.

Irene had felt a strange kind of shyness when it came time to actually give the gift to Molly. She feigned nonchalance as best she could, casually dropping the carrier bag on the arm of the sofa where Molly sat.

She wasn't one to give gifts, really, except when it gave her an advantage. She especially was not the type for spontaneous gifts.

Molly was not one used to receiving them.

Irene wears a fragrance that costs three times the one she'd bought for Molly, and goes through a bottle every two months. Molly has been nursing her precious bottle for six and it hasn't been depleted by half.

Irene sniffs the air again. Molly has been baking. Not recently. Perhaps some scones this morning. Underneath that, another very familiar fragrance. Lavender, citrus, woods, spice.

Molly's voice filters from the bedroom, a soft sigh. Irene smiles and steps out of her heels. She glides smoothly through the kitchen to the bedroom door, opening it halfway. Just enough to see, stopping right before the point where it would creak.

She leans against the door jamb and watches as her pathologist, sprawled out on the bed, writhes beneath the ministrations of her consulting detective.

Sherlock kneels at the end of the bed fully clothed. Molly likes that. Being exposed while the other person stays covered. He would shed his clothing eventually; she also likes the heat of his skin. She often says to Irene "He's so hot. Burning. it's like that mind is a steam engine." Irene knows, though her skin doesn't register quite as much heat from him. Then again, Molly also says that Irene runs almost as hot as Sherlock.

It isn't surprising, is it? No more surprising than the fact that she should worship this gentle little woman as much as Sherlock does. No more surprising than the fact that Molly loves Irene as much as she loves Sherlock.

What was it Sherlock had said, on a night three months ago, when the two of them sat waiting for Molly to come home from work?

"It's like a fire. You can have the fuel, and the heat, but you won't get a flame without air."

There it was, wasn't it?

They are both still oblivious to her presence. Molly's eyes are squeezed tight and Sherlock's back is to her. Irene looks closely at Molly, the way her body tenses when Sherlock puts his fingers inside her. The way she works her jaw.

"She doesn't like that," Irene admonishes.

Molly's eyes fly open and Sherlock lifts his head. He doesn't turn toward Irene.

"Well it took at least ten seconds longer than I thought it would for you to offer your opinion."

Of course he'd known she was there. He'd just chosen not to acknowledge her. He does get off on letting her watch. And watching.

Irene goes to Molly, lightly pushing Sherlock away and leaning over her on the bed. "Hello, darling. It's okay. I'll show him how to do it properly."

Sherlock has begun rubbing his hands over Irene's arse. She bats them away. "Not now, junior. Amateur hour is over."

Molly's eyes light up like it's her birthday and Christmas all in one. She lifts her head and kisses Irene, her mouth tasting of hot chocolate and peppermint Schnapps. One of Sherlock's hands is on Irene's waist and the other one is drawing down the zipper of her black sheath dress.

"Have you two been playing in the liquor cabinet again?"

"Just Molly," Sherlock says as he pulls Irene to her feet and slides her dress down her body and onto the floor. "She wants me to, as she so eloquently put it 'stick it in her arse' and thought that being a little tipsy would help her relax."

"Oh for God's sake," Irene says, turning to face Sherlock. She reaches up and grabs him by the hair at his nape, tugging none too gently and pulling his face to hers. She lightly licks the side of his mouth, just enough to get a small taste of Molly. She releases him and pushes away. "Good thing I came home early or our poor dear might have had to call in to work tomorrow."

"So you think you're better at that, too?"

"A penis isn't necessary for anal sex, Sherlock." She reaches behind her back and unhooks her bra, shrugging out of it and hanging it on the doorknob. Irene isn't sure if the look on his face is because of how much he enjoys her in only her knickers and thigh highs, or the thought of her pegging someone.

Probably both. He's still so wonderfully naïve, about some things, even after all these months.

"Excuse me?" Molly says. She's still sprawled on the bed. "Are you two going to keep arguing over who can fuck me better or are you going to actually fuck me?"

"Of course we're going to fuck you," Irene says, sitting beside Molly and stroking her hair. "But only if you really want to. How much have you had to drink?"

"Just one, and it was weak. We got distracted. I'm fine, and I want you. Both of you."

"But who do you want more," Sherlock says. He takes off his jacket and stretches out on the other side of Molly and runs his finger from the juncture of her jaw and neck all the way to the curls on her mons. Irene has to hand it to him; he does know all of the little things that get a girl's motor running. He dips his finger between Molly's legs briefly, then holds his hand out to Irene. She draws his finger into her mouth and sucks. Molly's eyes are like saucers as she pulls both of them to her.

Sherlock focuses on her lips while Irene ducks her head to pull one hard pink nipple into her mouth. She covers Molly's other breast with her hand, and Sherlock's hand covers hers. Sherlock lifts his head and their eyes meet for a heartbeat (his are icy blue at the moment) before Irene works her way further down Molly's body. Sliding off the bed, she settles in the same spot Sherlock had occupied previously, though she picks up his jacket and spreads it on the floor to kneel on. Molly is absently stroking Sherlock through his trousers as he licks and sucks her breasts.

"Sherlock," Irene says sharply. Both Molly and Sherlock turn their heads toward her. "Take your clothes off."

"Right now?" he asks.

"Molly would like to touch your cock, wouldn't you darling?"

Molly kisses Sherlock gently and smiles at him. "Please?"

He stands and untucks his shirt, then begins slowly unbuttoning it, starting with the cuffs. With Molly's attention fixed on Sherlock, Irene seizes the opportunity to put her mouth where Sherlock's had been when she walked in the room.

When Irene wraps her lips around Molly's clit, she arches her back so hard that she nearly bucks off the bed. But Irene is strong and steadies her hips with her hands, then winds her arms around Molly's thighs. She glances up to see Molly staring intently at Sherlock, who has removed his shirt and is slowly undoing his trousers as he stares back. The heat in their gaze sends a corresponding flash of heat from Irene's belly to her thighs and out to her very fingertips.

She continues to tease Molly's clit with her tongue while caressing her tummy with her fingers. She tastes delicious today. She mostly does taste wonderful but today it is especially nice. As Irene increases the pace and pressure of her tongue and lips, she very carefully slides one finger inside. This is where Sherlock went wrong. With Molly, you go slow and easy, at least at first. He seems to have grasped this concept when it comes to his dick, but had gotten a little too enthusiastic with his hands, hurting her when it should have felt incredible. Irene wonders why he didn't see the signs as quickly as she had. Perhaps he is testing boundaries.

As Irene presses a second finger into Molly and curls them back toward her g-spot, Molly pumps her hips in time with Irene's thrusts. Sherlock has completely undressed and is again lying beside her, his dick looking enormous in Molly's hand as she strokes him. Before long, though, she can't concentrate on anything but her own pleasure. She releases him and throws her hands over her face as her body tenses for a long moment before she relaxes with a low moan, pulsing beneath Irene's tongue and around her fingers.

The Woman crawls up onto the bed to hover over Molly, who folds her arms around her and pulls her close for a deep kiss. They stay like this for several minutes, exploring each other's mouths, hands roaming over each other's bodies. Sherlock watches, occasionally running his hand over Irene's bum and dipping a finger inside her knickers. Irene isn't fond of penetration, so he concentrates on her clit, ghosting his fingers along it and her outer lips.

Finally, Irene sits back, straddling Molly and grinning at Sherlock.

"I think you'll find she's relaxed enough now, no need for alcohol."

"Now why didn't I think of that?" he says.

"Because you're an idiot," Irene replies, cupping his cheek fondly. He takes her hand and slowly, torturously licks her fingers, the ones she'd had inside their Molly. Then he leans in and kisses Irene, drawing her bottom lip into his mouth and biting it before pulling away.

"You're going to walk us through it, right?" says Molly, pushing herself back fully on the bed and sitting up on her elbows.

"Obviously," says Irene, in her best Sherlock voice. He raises his eyebrow at her but concedes, stepping back and folding his arms across his chest, waiting for instruction. If he weren't Sherlock, he might look ridiculous, standing there looking so serious with his dick sticking almost straight in the air. But he is Sherlock, and he looks magnificent.

"You weren't planning on doing it without lube, were you?" she asks. He rolls his eyes and goes to the night stand, opening the drawer and pulling out an array of bottles. Irene chooses one and he puts the rest back. "You can do this in almost any position that you can with vaginal sex. But we'll just start out with Molly on her knees and you behind. It'll be easier for you both to control the depth of Sherlock's thrusts."

They both nod and Molly gets on her hands and knees.

"Kneel on the bed behind her, Sherlock. Fairly familiar, right?" She's watched him fuck her like this dozens of times. Sometimes sitting back with a glass of wine, and merely watching, other times berating Sherlock for his technique and threatening him with the riding crop.

Irene gives Molly an affectionate kiss on the cheek then squeezes lube in her hands and rubs them together to warm it.

"Now relax, darling," she says to Molly. "Sherlock, spread her cheeks, but nothing else." He did as he was told and Irene slowly eases a slick finger into Molly's arsehole. Molly cries out and Irene stops.

"Keep going," Molly says, her head down and breathing ragged. "Please."

Irene smirks and slides her finger in and out a few times before removing it.

"Sherlock's going to try now, okay?"

"Yes, please, yes!"

Irene warms more lube in her hands as she moves to kneel behind Sherlock on the bed. She reaches around and grabs his cock. He breathes in sharply at the strength of her grip, and thrusts gently as she spreads the lube over his length.

"Spread her wide," Irene says as she guides his cock toward her. "And go slowly. I know how hard you like to fuck her but she's not as resilient here."

"I won't hurt her," he says. Irene gives him lingering kiss at the base of his neck and moves her hands to his hips as he pushes forward.

"Oooh God," Molly moans as he enters her. She lowers her head to her the bed, resting her forehead on her arms.

"Go ahead," Irene says, giving Sherlock a pat on the bum. He moves slowly, finding a rhythm, watching, enthralled, as his cock slid in and out of Molly's arse.

Irene goes to the other end of the bed to check on Molly, who is back up on her hands. She kisses her and smooths her hair back from her sweaty brow.

"Irene," Molly sighs.

"Yes?"

"Take your knickers off. I want to-oh god—thank you."

"And how are you going to do that?"

"Just do it—take them off and lie down—"

"Do it," Sherlock says roughly. She looks at him and licks her lips. She's not sure if she's ever seen him looking this wrecked before. Irene shimmies out of her knickers and gets in bed, positioning herself in front of Molly.

"Do you want me to open my legs?" she asks.

"Yes—please." Molly says.

Irene does as asked.

"Do you want me to move closer?"

"Yes!"

"How are you going to thank me?"

"I'm going to make you-fuck—I'm going to make you come."

Irene scoots closer and Molly ducks down, resting on her elbows and gripping Irene's thighs. Irene throws her head back as Molly lapped at her relentlessly. She isn't as intricate in her technique as Irene, but she makes up for it with sheer enthusiasm.

When Irene opens her eyes, Sherlock is looking down at her, at them, his face so open, his fingers digging into Molly's flesh as he pumps into her. Molly's soft, lean back and lovely hair and her mouth worked in sync with Sherlock's body. They are perfect, the three of them, a complete circuit, and she would have cried with the joy of it if her orgasm hadn't taken her at that moment, obliterating all thought in a bright red blaze.

Molly cries out with her second orgasm while Irene lies panting, and Sherlock follows with a low groan. He grips Molly around the waist to keep her from falling and pulls out of her as slowly as he'd gone in. They collapse on either side of Irene, and there commences several minutes of cuddling and murmuring and soft kisses before they fall asleep in turn, each one connected to the other two by touch.


End file.
